1. Field
The disclosed embodiments relate to a ventilation system of a wide-bodied aircraft with a pressurisation cabin according to claim 1 and claim 16 respectively. More particularly the disclosed embodiments relate to a ventilation system for an aircraft with pressurisation cabin which comprises a compressor apparatus, several air outlets and at least one suction air intake pipe in the pressurisation cabin. The volume flow through the air outlets is set each time by a volume flow control member.
2. Brief Description of Related Developments
It is generally known that a system for ventilating the cabin of an aircraft comprises an air supply which draws fresh air in from the atmosphere outside of the aircraft in order to direct it into the cabin of the aircraft wherein the pressure in the cabin has to be adapted appropriately to the human organism, i.e. is to correspond at least to the pressure of 2000 m above sea level. The used air is drawn out through an extraction device in the cabin and directed to the outside. The air supply comprises as a rule a compressor which is driven by the engines of the aircraft and is connected to an air-conditioning device. The extraction device utilises the pressure difference between the outside and inside of the aircraft and comprises pressure control valves. This extraction device can likewise contain a turbine with which a part of the energy of the spent air can be recovered, more particularly to boost the drive motor of the supply compressor.
Particularly in the case of wide-bodied aircraft in which the interior is divided into a number of compartments such supply and extraction devices alone are not sufficient to guarantee correct ventilation. It is then necessary to provide means which permit air circulation in the interior of the aircraft.
In modern aircraft such as for example AIRBUS A 310 and A 320 or BOEING 727, 747, 757 and 767 the air circulation units contain a network of ventilation ducts and a number of electric fans of which some blow the air into the ducts and others suck the air out from the ducts. The ducts run in the floor in the aircraft in the compartments either side of the gangway and in the ceiling appliances above each seat (passenger seat units, PSUs). The circulation devices comprise a blower and a suction filter which are preferably mounted on a common shaft and are driven by a common electric motor. The fans are located underneath the floor of the cabin. An air mixer mixes fresh air from the supply device and air which was returned from inside the cabin, and distributes the mixed air into the compartments above the floor.
A ventilation system of this kind is known from DE 690 03 266 T2.
The ventilation system in the case of commercial aircraft thus comprises numerous air outlets and branch lines. The air flow through each of these air outlets is determined by fixed orifice plates installed in front of the respective air outlet to define the cross-section available for the flow. Thus by way of example the air flow through an air outlet which is located close the compressor of the air supply has to be reduced. On the other hand the air flow through an air outlet which is located further away from the compressor has to reach the cabin unobstructed as far as possible. In the first case therefore it is favourable to select a relatively small cross-section for the orifice plate. In the second case a large cross-section will be selected in order to compensate for the drop in pressure over the pipe system.
It is evident per se that exchanging such orifice plates at the two locations in the aircraft would lead to undesired effects resulting in an unfavourable air exchange in the cabin and possibly even leading to a permanent draught in the cabin. If an error of this type is discovered in the ventilation system after the ventilation system has been installed then extensive checks have to be made to trace the fault and find its cause. According to the prior art for this the pipe system of the ventilation system has to be dismantled at least in part in order to be able to then replace the defective or transposed orifice plates. However it is not always possible to localise the fault precisely so that in some circumstances the ventilation system has to be opened up at several locations in order to be able to replace the faulty orifice plate. It may indeed be the case that as a result of wrongly inserted orifice plates an air flow is produced in the cabin, but the presence of such air flow can still not automatically recognise which orifice plate was inserted just wrongly or whether there are perhaps even several orifice plates which have to be exchanged.
The procedure up until now according to the prior art is thus very laborious and does not always lead directly to the desired success.